The present invention relates, in general, to vehicle windshield or wiper assemblies and, more specifically, to vehicle windshield wiper assemblies having pedestrian collision safety features.
In vehicle windshield wiper assemblies, wiper blades are mounted on wiper arms. The wiper arms, in turn, carry a mount which is attached to a rotatable pivot shaft. The pivot shaft is rotatably mounted in a pivot shaft housing or holder fixedly mounted on vehicle structure, such as on the vehicle plenum or cowl panel immediately below the lower edge of the vehicle windshield. Linkages connect the pivot shaft of one wiper arm to the pivot shaft of the other wiper arm to impart reciprocal motion to both wiper arms when the motor reciprocally drives the one pivot shaft.
Recent studies have shown that pedestrians have a high likelihood of injury when struck by a vehicle traveling at certain speeds. Such injuries occur when the pedestrian is thrown by impact with the front bumper or front edge of the vehicle hood onto the hood where the pedestrian""s head and/or torso then contacts the windshield area with considerable force.
Although windshield wiper assemblies are provided in a large number of different configurations, typical wiper assemblies have the upper end of the pivot shaft and, the wiper arm attached thereto protruding above an impact line nominally defined by the exterior surface of the vehicle hood. As the pivot shaft, although rotatable in the pivot holder, is nevertheless fixed relatively to the vehicle structure, the protruding portions of the pivot shaft act as a fixed object which increases the likelihood of serious injury to a pedestrian during a collision between the pedestrian and a vehicle.
Certain countries or regional groups have initiated legislation to protect pedestrians and other road users in the event of a collision with a vehicle. Under such legislation, manufacturers will have to insure that the pivot shafts do not act as an external projection during a pedestrian collision with a vehicle.
As a result, windshield wiper manufacturers have provided a number of pivot shaft mounting arrangements which are capable of pivoting below the hood impact line or breaking away from the fixed mount to the vehicle structure and dropping below the vehicle hood so as to lower the protruding portion of the pivot shaft and the wiper arm below the impact line during a pedestrian collision. Such mounting arrangements rely on an impact force of a predetermined amount between the pedestrian and/or the vehicle hood which typically crumples and moves out of its normal position during a collision to initiate the pivoting or break away movement of the pivot shaft from its fixed mount to the vehicle structure.
One such pivot housing mounting arrangement has a weakened portion formed in the arm extending between the pivot shaft holder to the mounting end which is fixedly attached to the vehicle. Impact of the hood and/or the pedestrian with the pivot shaft above a predetermined force level results in a fracture and breaking away of the pivot shaft holder from the mounting end of the arm thereby allowing the pivot shaft holder to drop below the hood to minimize a fixed impact with a pedestrian thrown onto the hood during a collision with the vehicle.
However, it has been found that the force loading on the pivot shaft housing generated during impact of a pedestrian thrown onto the vehicle hood during a collision with the vehicle can vary considerably depending upon the angle of impact between the pedestrian and the protruding end of the pivot shaft. This could result in only a portion of the impact force being transmitted to the pivot housing which may be insufficient to initiate the fracture and breakaway of the pivot housing thereby resulting in the wiper pivot housing remaining as a fixed external object which can contact the pedestrian.
It is also known that vehicle hoods are designed as energy absorbing crumple panels which absorb a portion of collision impact forces. Thus, during a collision between the vehicle and a pedestrian, the forces impacting on the hood by impact of the pedestrian on the hood will initially be absorbed by deformation of the hood. This reduces the magnitude of impact forces of the pedestrian on the protruding portions of the wiper assembly which again may result in insufficient force being transmitted through the pivot shaft to the housing to initiate the break away of the pivot housing. At the same time, the wiper assembly must present a solid mount for torsional loading and radial force management.
Thus, it would be desirable to provide a vehicle windshield wiper apparatus having a break away pivot housing which overcomes the above-described problems in prior art windshield wiper systems having pedestrian impact safety capabilities. It would also be desirable to provide a vehicle windshield wiper apparatus which provides a break away or frangibility of a component of the wiper apparatus from the fixed mount to the vehicle at an earlier stage during a pedestrian collision. It would also be desirable to provide a vehicle windshield wiper apparatus in which pedestrian impact forces on the vehicle hood or cowl panel are maximized to ensure pivot shaft break away at a minimum predetermined impact force level, while, at the same time, maintaining robust operating characteristics for the wiper assembly.
The present invention is a wiper apparatus having unique pedestrian impact safety features.
In one aspect of the invention, the wiper apparatus includes one or more components, such as a pivot shaft or drive motor, which are fixedly connected to stationary vehicle structure via a mount. A fracture portion is formed in the mount which is capable of fracture under a predetermined force applied thereto to separate the wiper component from the portion of the mount fixed to the stationary vehicle structure to allow lowering of the wiper component below the vehicle structure. An energy focus member is carried on the vehicle structure subject to collision force to focus movement of the vehicle structure due to the collision force onto the fracture portion of the mount.
The energy focus member may be one or more arms fixedly carried on the vehicle structure subject to movement during a collision. The one or more arms may be provided with one or more impact ends normally disposed in proximity with the fracture portion of the mount.
The frangible portion may be defined by an aperture or slot or at least one open ended notch formed in the mount.
The unique energy focus member of the present invention ensures that a sufficient force is generated during a pedestrian collision to initiate separation of the mount from the end fixed to the vehicle structure so as to allow the wiper component to lower below the vehicle hood impact line earlier in time in the collision sequence so as to ensure that external portions of the wiper apparatus have safely moved below the impact line before a pedestrian can contact such external portions.
In one aspect of the invention, the wiper component fixed to the vehicle structure via the mount is a wiper pivot housing carrying a rotatable wiper arm pivot shaft. At least an end portion of the pivot shaft extends externally of the vehicle impact line in a normal mounting position. In another aspect, the frangible portion of the mount engaged by the energy focus member fixedly connects the wiper apparatus drive motor and/or the wiper apparatus frame to the stationary vehicle structure. In this aspect, fracture of the mount by the energy focus member allows the drive motor and/or frame to lower to prevent contact with a pedestrian thrown on the vehicle hood during a collision.
The unique energy focus member of the present invention may be easily implemented in a low cost manner to initiate the fracture and separation of one or more of wiper apparatus mounts to the vehicle. In addition, the energy focus member uniquely directs the collision forces generated by the vehicle hood into the fracture portion of the mount. This overcomes the problem with previous frangible pivot housing designs in which the force directed only along the longitudinal axis of the pivot shaft which causes the separation of the pivot housing from the fixed mounting end of the pivot housing varied considerably depending upon the angle of force impact on the exposed portions of the wiper apparatus. The present energy focus member and frangible mount also enables the entire wiper apparatus to have a robust design to resist radial force and torsional loads during normal wiping operation without compromising the pedestrian""s safety features afforded by the frangible mount and energy focus member of the present invention